Several years ago, Sibill Schilter, a student at the University of Zurich, learned that her school was recruiting people to test whether a smartphone app could help someone change their personality traits. These are people’s patterns of thoughts, emotions, and behaviors, and they’re commonly categorized as the “big five”: openness, conscientiousness, extraversion, agreeableness, and neuroticism.
Curious to learn more about herself, Schilter signed up. Maybe, she thought, she was a little too agreeable. “I’m the person who always wants to please everyone a bit, and I can get better at saying no when I don’t want something,” Schilter says.
For decades, psychologists have debated whether these traits are fixed or changeable. The study that Schilter participated in was designed to test whether using an app daily for three months would be enough to create noticeable and lasting personality changes. Each participant chose one trait they wanted to increase or decrease. For instance, one goal could be to become more extraverted, which the researchers defined as being more sociable, having more energy for action, being less quiet, or taking the lead more often.
The app, called Peach (PErsonality coACH), works like a diary, a dashboard, and a text messaging channel rolled into one. On the dashboard, users can see an overview of their goal, a calendar that shows their progress, and their task for the week. For instance, someone who wants to be more conscientious may be assigned to do homework for one hour after coming home from classes. The app sends the user two push notifications every day to remind them, and if the user makes progress it will show up on the dashboard.
Users can also talk with a sort of digital coach, a chatbot also named “Peach,” about their daily activities. The chatbot might ask which task someone is working on or how stressed they are. Users can also opt to complete a daily diary, doing a self-assessment of those five main personality traits. (For example: “How would you describe yourself today—shy or outgoing?”)
In a study published in February in Proceedings of the National Academy of Sciences the researchers concluded that the app works. The study was conducted with 1,523 volunteers. Compared to the control group, the users who received the smartphone intervention showed more self-reported personality trait changes toward their goals. Overall, friends, family members, or intimate partners who volunteered to observe the participants also noticed the personality changes, with both self- and observer-reported changes persisting three months after the end of the study. Notably, the observer-reported changes were only significant among those who desired to enhance a trait, but not for those wanting to minimize one, suggesting it’s perhaps easier for others to observe when a person is enhancing a trait compared to getting rid of one.
Mirjam Stieger, the lead author on the study, describes the “high dosage” nature of the intervention—that users interacted with the app and the chatbot several times a day—as key to driving personality changes. “It’s the repetition that helps,” says Stieger, a postdoctoral fellow in the Lifespan Developmental Psychology Laboratory at Brandeis University.
Mathias Allemand, the principal investigator on the project, agrees, adding that other interventions people may try, like seeing a therapist or attending meditation sessions, typically are less intensive, occurring every week or two. He adds that the accessibility, convenience and variable nature of the app—like being able to have different conversations with the chatbot every day—made it appeal to participants. “You have the smartphone and [chatbot] coach in your pocket,” says Allemand, a professor of psychology at the University of Zurich.
“I really liked it—every week, you had a goal to pursue,” agrees Schilter. “You always have your smartphone, so there was less of a barrier.”
Still, she notes her adherence to the app’s instructions wasn’t always perfect. Some weeks Schilter fulfilled the task assigned to her, and some weeks she didn’t. For instance, she completed tasks like saying no if someone asked her for something that she didn’t really want to do, and writing down a list of things she wants to achieve or experience in the next five years. But she wasn’t able to complete a task about not letting anyone cut in front of her in line—because nobody tried to. (This was before Covid-19, when strangers got closer to one another.) Yet she says using the app did cause her to reflect on the times it had occurred in the past.
Allemand says that one way the app helps is by reminding people of the discrepancy between what they’re doing and what they want to achieve. If the user isn’t moving closer toward their goal—whether measured through self-assessments or completion of the weekly tasks—an icon on their dashboard will flash yellow (for no change) or red (if the change is in the opposite direction.) Just like receiving counseling, apps can supportively hold people accountable by keeping them on task and engaged.
Eventually, Schilter’s app notified her that she’d achieved her goal of being less agreeable: It gave her a green light on her dashboard and an encouraging message, along with a reminder to keep practicing the skill. “I am now better at standing up for my opinion or saying when I do not like something,” Schilter says. “Also, it feels more OK to be less agreeable in some situations.”
The friends who’d offered to be Schilter observers filled out three online surveys about her personality—one a week before she tried the app (as a pretest), one a week after the 10-week trial period (as a post-test), and another 12 weeks after that. After the study, they scored her as being better able to stand up for what she thought.
While some experts still hold the idea that personality is fixed, these days “the majority of experts believe that personality traits change across the life course,” says Brent Roberts, a professor of psychology at the University of Illinois at Urbana-Champaign and a coauthor on the study.
“People’s personality changes through maturation,” agrees Rodica Damian, an assistant professor of social psychology at the University of Houston, who was not involved in the study. “For instance, as we age, most people become more conscientious and agreeable, and less neurotic, to help cope with life.”
However, experts stress that someone has to want to change their personality because they are dissatisfied with certain situations or aspects of their lives. And ultimately, the change comes from the person. “It’s not the app that changes people. People change themselves,” Allemand says. “An app is a means to an end.”
As a study participant, Schilter feels the same way. “You have to want to change. You have to want to reflect on yourself. You need some time every day. It’s not much, but it’s still minutes of your daily life,” she says.
Damian says she was impressed by the study. “It’s very much evidence-based,” she says. “It has the potential to provide a more accessible intervention that can contribute to quick, personalized change” compared to other therapeutic approaches. That said, she points out, because the follow-up period was 12 weeks, “we don’t know yet how long-lasting the change is beyond that period.”
Stieger and Allemand hope to explore this question by looking at a subset of participants who will provide data after one year via a questionnaire. Additionally, the research team also collected data from the users’ smartphones—so-called digital footprints—including the number of phone calls and text messages they send and receive, and the number of nearby devices detected via Bluetooth. The researchers plan to examine whether metrics like sending a higher number of phone calls or texts are indicative of someone becoming more extraverted.
The study had some other limitations: Most notably, the researchers excluded subjects with an underlying psychological problem, like depression, as the app wasn’t designed to replace clinical therapy. The authors envision it as one tool in a kit that a user or their therapist might try when addressing less clinical aspects of personality, like shyness, rather than conditions like anxiety. And they say it might be useful for people who live in rural areas where there’s less access to in-person therapy.
Roberts hopes that these novel findings help reframe the way we broadly think about human nature. Personality, he says, “is a consistent thing but it is changeable. The question is not whether it is, but how and whether we want to change it.”